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1 Copyright © ODL Jan 2005 Open University Malaysia Application of diodes Rectifier circuits Rectifier circuits Clipper circuits Clipper circuits Clamper.

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Presentation on theme: "1 Copyright © ODL Jan 2005 Open University Malaysia Application of diodes Rectifier circuits Rectifier circuits Clipper circuits Clipper circuits Clamper."— Presentation transcript:

1 1 Copyright © ODL Jan 2005 Open University Malaysia Application of diodes Rectifier circuits Rectifier circuits Clipper circuits Clipper circuits Clamper circuits Clamper circuits

2 2 Copyright © ODL Jan 2005 Open University Malaysia Rectifier circuits Circuits that convert an ac signal into a dc signal Circuits that convert an ac signal into a dc signal Two types: Half-wave rectifier & Full- wave rectifier Two types: Half-wave rectifier & Full- wave rectifier

3 3 Copyright © ODL Jan 2005 Open University Malaysia Half-wave rectifier

4 4 Copyright © ODL Jan 2005 Open University Malaysia Half-wave rectifier

5 5 Copyright © ODL Jan 2005 Open University Malaysia Full-wave rectifier

6 6 Copyright © ODL Jan 2005 Open University Malaysia Full-wave rectifier

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9 9 Copyright © ODL Jan 2005 Open University Malaysia Clipper Circuit Clipper circuits have the ability to clip off a portion of the input signal without distorting the remaining part of the alternating waveform. Clipper circuits have the ability to clip off a portion of the input signal without distorting the remaining part of the alternating waveform.

10 LP3 10

11 Clamper Circuit

12 12 Copyright © ODL Jan 2005 Open University Malaysia Clamper Circuit The clamping network clamp a signal to different dc level without altering the wave-shape. The clamping network clamp a signal to different dc level without altering the wave-shape. The network will have a capacitor, a diode and a resistive element. The network will have a capacitor, a diode and a resistive element. The magnitude of R and C must be chosen such that the time constant t = RC is large enough to ensure that the voltage across the capacitor does not discharge significantly during the interval the diode is non- conducting The magnitude of R and C must be chosen such that the time constant t = RC is large enough to ensure that the voltage across the capacitor does not discharge significantly during the interval the diode is non- conducting Used in TV receivers as a DC restorer Used in TV receivers as a DC restorer

13 Diode :- Clamper Positive Clamper The circuit for a positive clamper is shown in the figure. During the negative half cycle of the input signal, the diode conducts and acts like a short circuit. The output voltage V o 0 volts. The capacitor is charged to the peak value of input voltage V m. and it behaves like a battery. During the positive half of the input signal, the diode does not conduct and acts as an open circuit. Hence the output voltage V oV m + V m This gives a positively clamped voltage. V o V m + V m = 2 V m

14 Diode :- Clamper Positive Clamper

15 Diode :- Clamper Negative Clamper During the positive half cycle the diode conducts and acts like a short circuit. The capacitor charges to peak value of input voltage V m. During this interval the output Vo which is taken across the short circuit will be zero During the negative half cycle, the diode is open. The output voltage can be found by applying KVL.

16 Diode :- Clamper Negative Clamper

17 Diode :- Clamper Biased Clamper

18 Diode :- Clamper The circuit of a positively biased clamper is shown in the figure. During the negative half cycle of the input signal the diode is forward biased and acts like a short circuit. The capacitor charges to V i + V s. Applying the KVL to the input side During the positive half cycle of the input signal, the diode is reverse biased and it acts as an open circuit. Hence V s has no effect on V o. Applying KVL around the outside loop.

19 LP3 19 In the positive half cycle C gets charged through D to 10V (peak of sine wave + 5 V) with the straight plate of C at a higher potential. D Clips the output to a maximum of -5V. In the negative half cycle D is reverse biased. The output can reach a minimum of –15V (-V C + negative peak of sine wave). How Does A Clamp Circuit Work?


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